Baking and roasting oven

ABSTRACT

A baking and roasting oven for cooking food has a muffle structure having a front face which defines a charging opening for receiving the food to be cooked. Guide members are fixedly mounted with respect to the muffle structure and a door assembly having a door extending substantially parallel to the front face is also provided. The door assembly includes carriage members which are connected with the door. The carriage members are arranged beneath the muffle structure in spaced relation to the door. The carriage members movably engage the guide members and so facilitate the movement of the door between open and closed positions. A locking mechanism is disposed with respect to the guide and carriage members for locking the door when the door is in the closed position.

' [22 Filed:

United States Patent [191 Detterbeck et a1.

[.54] BAKING AND ROASTING OVEN [75] Inventors: Heinrich Detterbeck; Josef Ackermann; Bruno Schmalzgruber, all of Traunreut, Germany [73] Assignee: Siemens-Electrogerate GmbH, Berlin,Germany Feb. 16, 1971 [21] Appl.No.: 115,195

[30] Foreign Application Priority Data Feb. 13, 1970 Germany ..P 20 06 621.1

[52] US. Cl. ..l26/197, 126/273 R [51] Int. Cl. ..F24c 15/02 [58] Field of Search ..l26/l9 R, 21 R, 39 R,

[56] References Cited UNITED STATES PATENTS 11 3J7fi [451 May 29, 1973 3,565,054 2/1971 Smith et al ..l26/200 X Primary Examiner-Edward G. Favors Att0rneyCurt M. Avery, Arthur E. Wilfond, Herbert L. Lerner and Daniel J. Tick [5 7 ABSTRACT A baking and roasting oven for cooking food has a muffle structure having a front face which defines a charging opening for receiving the food to be cooked. Guide members are fixedly mounted with respect to the muffle structure and a door assembly having a door extending substantially parallel to the front face is also provided. The door assembly includes carriage members which are connected with the door. The carriage members are arranged beneath the muffle structure in spaced relation to the door. The carriage members movably engage the guide members and so facilitate the movement of the door between open and closed positions. A locking mechanism is disposed with respect to the guide and carriage members for locking the door when the door is in the closed positron.

22 Claims, 13 Drawing Figures PATENTEDMAYZQ I973 SHEET l I]? 3 SHEET 3 BF PATENTED W29|975 lation from the door beneath the muffle. Also provided is a carrier for carrying the charge to be placed in the "oven. The carrier is adjustably mounted on the inner side of the door. The arrangement according to the invention is especially applicable to ovens which are heated electrically.

In present day hinged doors used in baking and roasting ovens difficulties arise in connection with sealing the inner space of the muffle with the aid of these hinged doors. This is especially true if the doors are to press against the charge opening of the muffle with approximately the same pressure about the entire periphery of this opening. Acknowledging the existence of the usual fabrication tolerances, these difficulties are attributable to the condition that this type of door must first lie against the lower edge of the muffle opening and so leave a gap at the upper edge of the muffle.

Accordingly, it is an object of our invention to provide a baking and roasting oven wherein a tight sealing of the inner space of the muffle is achieved. Subsidiary to this object, it is another object to provide a baking and roasting oven wherein the door, muffle and locking mechanism of the oven are arranged to achieve a tight sealing by the door of the inner space of the muffle when the temperature therein undergoes changes over a range of as high as 600C, for example, as in the case of self-cleaning ovens.

The objects of our invention are of special significance where self-cleaningoperation is achieved with the aid of circulated hot air in a fully closed system, for example as disclosed in the copending CIP application of J. Ackermann, filed on Nov. 27, 1970, Ser. No. 93,364 and now U.S. Pat. No. 3,678,245, and entitled: Device for Cleaning the Walls of the Muffle Chamber of Baking and Roasting Ovens. The parent application of this CIP is the application of J. Ackermann filed on June 20, 1969, Ser. No. 834,947 and entitled: Method and Device for Cleaning the Muffle Walls of Baking and Roasting Ovens and the like.

It is another object of our invention to provide an arrangement of the door, muffle and locking mechanism which is adaptable to afford security against the possibility that a user of the oven will inadvertently open the door after the temperature inside the muffle has exceeded a definite value.

A baking and roasting oven constructed as required by the invention has a muffle structure with a front face defining a charging opening for receiving the food to be cooked. A guide means is fixedly mounted with respect to the muffle structure and a door assembly having a door extending substantially parallel to the front face movably engages the guide means via carriage means connected to the door and arranged beneath the muffle structure in spaced relation to the door, whereby the door assembly is movable-between open and closed positions. According to a feature of the invention, a locking mechanism is disposed with respect to the guide means and the carriage means for locking the door when the door is in closed position.

It is especially advantageous if the locking means'in configured so as to comprise a latching member and a locking member. One of these members can be mounted on the door assembly while the other member is mounted with respect to the muffle structure so as to engage the first-mentioned member to tightly close the door when the door assembly moves into its closed position.

The guide means for the door assembly can be for example, two guide rails mounted on the muffle structure and the carriage means can, for example, comprise two carriage parts of the door assembly respectively engaging the guide rails. According to another feature of the invention, it is advantageous to locate the lockingmechanism at the mid-location between the guide rails and carriage parts. In this way, the parts of the locking mechanism can work together with the lower end of the frame or structure of the door assembly or with a cross member provided at any location to join together the carriage parts. The locking member of the locking mechanism can be arranged either on the muffle structure or on the door assembly.

The carriage parts of the door assembly and the position of the door relative to the front face of the muffle is preferably so arranged that a surface region of the door lying adjacent the carriage parts faces the front face or annular edge surface of the muffle defining the charging opening so that these surface regions lie against each other when the door is closed. The door is resiliently biased toward this annular edge surface, whereby the surface region of the door abuts the edge surface. The locking mechanism includes a latching member and locking member as well as a drive means for applying a force to these members to press the door against the muffle edge surface. The force is directed along a line of action disposed between the carriage parts.

The resiliently biased door arrangement can be achieved by an elastic coupling of the muffle to the carrying frame and/or by a corresponding elasticity of the door assembly or of the carriage parts to which the door is attached.

The locking member and latching member are preferably so arranged that these members are movable re1- ative to each other. According to a further feature of the invention, the locking member and latching member are so arranged as to be movable relative to each other and the locking mechanism is provided with a drive means for driving one of these members. Also provided is a means for positioning the other member so as to permit the latter to move in a path having a travel component parallel to the guide means when the latching and locking members become mutually engaged. According to a still further feature of our invention, the simplest configuration to achieve this engagement includes a wedge-shaped member moveable transverse to the carriage parts and relative to said latching member.

The invention will now be described with reference to the drawings, wherein:

FIG. 1 is an elevation view of a section of the baking and broiling oven of the invention taken along line I-I of FIG. 2;

FIG. la illustrates an angle, greatly exaggerated, that is formed by the door of the oven and the front face of the muffle of the oven;

FIG. 2 is a bottom view of the oven.

FIG. 3 is a side view of the locking mechanism of the oven of FIG. 1 in its locked position;

FIG. 4 is a plan view of the locking mechanism of FIG. 3;

FIG. 5 is a view of the locking mechanism of FIG. 3 with the locking mechanism in its open position;

FIG. 6 is another embodiment of the locking mechanism in its open position;

FIG. 7 is a perspective view of the locking mechanism of FIG. 6 in its closed position;

FIG. 8 illustrates schematically the cam disc, switches and current circuits for the drive motor for the embodiments of the locking mechanism illustrated in FIGS. 3 to 7;

FIG. 9 illustrates, in perspective, a fragmentary portion of the oven according to the invention viewed from the back and equipped with a motor actuated vapor release mechanism;

FIG. 10 is a section taken of the vapor release mechanism according to FIG. 9;

FIG. 11 illustrates the coupling of jalousie slats to the drive motor; and

FIG. 12 illustrates details of the arrangement according to FIG. 11 in an enlarged view.

In FIGS. 1 and 2, reference numeral 1 designates a carrying frame schematically illustrated. Secured to frame 1 are a muffle 3 and guide portions 11 for the door assembly, the latter comprising carriage parts 21 and door 2. The support members or carriage parts 21 of the door assembly are borne by guide portions 1 1 via rollers 212 journalled in the carriage parts. The carriage parts 21 have angle portions 211 which extend upwardly into door 2. The angle portions are securable to door 2 so that the position of door 2 relative to the front face of the muffle 3 defines an acute angle as illustrated in FIG. 1a. The position of the door with respect to the front face 31 of the muffle is preferably selected so that the door 2 and front face 31 form the sides of a very small, acute angle that opens toward the door assembly as illustrated in FIG. 1a. A carrier 22 is adjustably mounted to the inner side of door 2 for accommodating the food to be placed in the oven. In addition, the inner surface of the door 2 is provided with a seal 23 and the charging opening of the muffle 3 is designated by reference numeral 32.

A locking mechanism 4 is disposed between the guide rails 11 so that its locking lever or locking member 41 couples with latching member 42 on transverse rail 12 of the frame 1. The locking member 41 is situate on a transverse rod 213 connecting the end portions of the carriage parts 21 of the door assembly. Details of this locking mechanism are illustrated in FIGS. 3 to 5 in enlarged illustration.

Referring to FIGS. 3 to 5, on transverse rail 12, a carrier 40 for a drive means is mounted. The drive means can be, for example, a motor. The motor is not illustrated in FIGS. 3 to 5 and has a drive wheel designated by reference numeral 50. The drive wheel 50 engages a tooth gear 51 which gear carries the latching member 42, the latter, for example, being in the form of a cylinder. The drive wheel 50 and toothed gear 51 together constitute a coupling means for coupling the latching member 42 to the drive means. The latching member 42 describes a circular path when the motor is running. A cam disc 8 is connected with tooth gear 51 and works together with the actuating arm of a switch 91 (see FIG. 8). The cam 8 is dimensioned so that the switching position illustrated in FIG. 8 is first obtained when the locked position illustrated in FIG. 3 is reached. The switch position indicated by the dotted line in FIG. 8 for the switch 91 is obtained first when the unlocked position illustrated in FIG. 5 is reached.

The locking member 41 is borne on the transverse rail 213 via a screw 214 in such a position that the turning axis of the latching member 42 and the bearing point of the locking member 41 lie on a line 7 (FIG. 4) parallel to the support member of the door assembly. In this way, the door assembly exercises no turning moment on the drive motor when held in the closed position. The drive motor is illustrated schematically in FIG. 8 by reference numeral 5. The locking member 41 has an elongated opening or slot 412 which makes possible the movement of the locking member parallel to the guide rails. A spring 6 acting between the transverse rail 213 and locking member 41 serves in cooperation with the slotted opening 412 for balancing out manufacturing tolerances and insures nonetheless a definite closing pressure between the door 2 and the front face 31 of the muffle 3.

Locking member 41 has a hook-like end portion 411 and is held in a rest position with the aid of a stop by the spring 6 in the position illustrated in FIG. 5 in which the hook-formed end portion 411 projects into the circular path of the latching member 42 whereat the latter can engage the locking member 41 at the rest position for pulling the same along the circular path to a next position to tightly close the door. Thus, a positioning means is provided which positions the locking member 41 relative to the latching member 42 for facilitating the mechanical engagement of the former by the latter. The positioning means includes the pivot bearing location or slot 412, spring 6 and the stop, the latter being mounted, for example, to the transverse rail or cross member 213. The path of travel of the latching member between the rest position of the locking'member and the next position thereof includes a travel vector extending in a direction parallel to the carriage parts. The coupling means is configured so that the length of the travel vector is less than the length of the slot.

A switch 94 (FIG. 3) is likewise arranged with respect to the outer portion of the hook-like end portion 411 with whose assistance in the closed position of FIG. 4 a switching function is achieved,'for example electrically connecting heating element of the heater disposed beneath the muffle.

The entire arrangement is so laid out that the component of travel of the latching member 42 extending parallel to the carriage parts 21 between the position at which the latching member comes against the end portion 411 of the locking member 41 and its closed position as illustrated in FIG. 4 is smaller than the slotted opening 412. The position at which the latching member 42 comes against the end portion 41 1 of the locking member 41 corresponds to the position of the door assembly at which the door 2 just touches against the front face 31 of the muffle 3. In this manner, an overloading of the motor is prevented. The closing pressure is determined by the spring 6.

A second embodiment of the motor-actuated locking mechanism is illustrated in FIGS. 6 and 7 which correwedge-shaped flange 431 arranged around the axis of rotation of the sector member. For this locking member there is provided a recess or receiving means 44 in the door 2 and a spring member 441 arranged in the door. The recess and spring member here perform the function of the latching member of the embodiment illustrated in FIGS. 3 to 5. When the motor 5 is running,

the segment-shaped member 43 is turned from the position illustrated in FIG. 6 to the closed position illustrated in FIG. 7 whereby, with an increasing turning anglc, an ever increasing force is applied to the door 2 via the spring member 441. With this force, the door 2 is pressed against the frame, that is, against the front face 31 of the muffle 3. This embodiment of the locking mechanism is, according to the invention, also useful for various purposes in connection with the doors of any desired configuration. I g

The control arrangement illustrated in FIG. 8 of the locking mechanism according to FIGS. 3 to 7 arranged for motor 5 is especially dimensioned for baking and broiling ovens equipped for self-cleaning operation, but is not limited to a special construction of the door. There is provided a temperature dependent switch 93 located in heat contact with the muffle 2. Switch 93 forms part of the circuit for the excitation winding 920 of a chang over control contactor 92. Switch 93 switches to the position illustrated in FIG. 8 when the temperature of the muffle reaches a specific upper limit, for example that temperature whereat the oven goes into its self-cleaning mode of operation. The switch 93 opens when the temperature in the muffle drops beneath a specific lowerboundary value. The motor 5 is connected in series to a voltage source R, Mp via the contacts of switches 91 and 92.

The muffle of every oven has a vapor opening through which the vapors occurring during broiling or baking in the muffle can be vented. During the selfcleaning operation with hot air rotating in a closed system, this opening must be closed. FIGS. 9 and 10 illustrate a suitable mechanism for this purpose whereby the closing and opening of the vapor vent is controlled by means of the motor 5 arranged with respect to the locking mechanism. The vapor vent 33 arranged in the muffle 3 is closed by means 'of a flap 341 loaded by a spring 349'- and arranged in a vent housing 34. For sealing, there is provided a seal 342 mounted with respect to the vent housing 34 is a rod 343 and a bell crank 344 which is rotatable at pivot 345. The flap 341 is coupled to an arm 349 (FIG. 3) by means of rod 343 and a bell crank 344 via a pull cable 346 and directional rollers 347 and 348. The arm 349 can be driven by motor 5. The coupling of arm 349 to flap 341 is such that the latter is held by means of spring 349 in the closed position illustrated in FIG. 10 only when the latching member 42 of FIG. 4 is in its closed position. In this way the opening of the flap 341, which is desired for reasons of safety, is possible against the force of spring 349 with a corresponding overpressure in the muffle. In contrast,

during the normal baking operation or by an open muffle, the flap 341 is lifted.

The vent housing 34 has a circular shaped opening directed to the outside with a circular formed elastic seal 300. The seal 300 lies elastic against the ridge 3401 of a channel 340 that serves to direct vapor away because the outer diameter of the ridge 3401 is greater than the outer diameter of the channel and is also greater than the inner diameter of the seal 300. In this manner, a safe and tight seating is guaranteed when the high temperatures of the self-cleaning operation and the associated expansion occur.

Not illustrated in the drawings is a channel containing a hot air blower and an after-burner. The channel exits at one location of the muffle and enters the muffle at another location. It is preferable to construct this channel in two parts whereby the blower and afterburner can be joined with each other in the same manner as illustrated in FIG. 10 for channel 340 and the vent housing 34.

With a baking and roasting oven provided with a door window, it must be ensured that the specified upper temperature limit on the outer side of the window is not exceeded during self-cleaning operations. According to the embodiments illustrated in FIGS. 11 and 12 a door 2 with inner and outer windows is provided with jalousie slats 25 disposed between these windows. The slats are automatically closed for the selfcleaning operation. In this connection, it is preferable that the motor 5 arranged with respect to the locking mechanism be coupled to the jalousie slats 25 by means of a rod 254 directed through an opening 311 at the edge of the muffle 3 as well as by means of a bell crank member or lever portion 253 and an actuating means 252. The rod 254 is preferably held in an end position by means'of a spring. In this position, the jalousie slats 25 are held in the open position illustrated in FIG. 11 when the door 2 is closed. This position is determined by means of a position wheel 255 and a cam disc 256. As soon as the motor causes the door to lock, rod 254 moves into a second position in which the jalousie slats 25 are released and fall into their closed position. The jalousie arrangement of this type for protecting the outer window of the door is also applicable to a hinge pivoted door and can also be actuated manually.

Finally, it is now pertinent to describe the functional cooperative relation of the above-described parts during a self-cleaning operation wherewith a switching clock can be arranged on the baking and broiling oven. Such a clock can also serve other control purposes and can hold the temperature in the muffle to an adjustable value by means of a regulator. This regulator should be arranged so that a reference temperature value of about 500C can be set which is required during selfcleaning operation. On the switching clock the desired cleaning time is then set and a temperature selector of the regulator is positioned to the self-cleaning mode. For reasons of safety, a pressure switch is provided which must additionally be pressed before the selfcleaning operation can be initiated with the time clock.

All preconditions being satisfied, the time clock first actuates the heating body for the upper heater of the muffle so that the baking oven is slowly heated and fat deposits in the muffle are dried out without the development of smoke. For example, with a temperature of approximately 280C, the switch 93, described in connection with FIG. 8, is actuated and goes into the position illustrated in FIG. 8, whereby the contactor 92 goes into the position illustrated in FIG. 8 and a voltage is applied to the motor because the switch 91 is lo cated in the position illustrated by the dashed line in the presence of an unlocked door. With the motor 5 running, latching member 42 moves out of the at rest position illustrated in FIG. 5 in a counter-clockwise direction to the position illustrated in FIG. 4 and takes the locking lever member 41 along. In the closed position, the motor 5 automatically switches to the off position with the aid of the cam disc 8 because then the switch 91 goes into the position illustrated in FIG. 8 by the solid line and the contactor 92 is still excited.

The stove continues to operate in this manner also when the door of the oven is open to the extent that the latching member 42 and the locking lever member 41 are just still mutually engaged. With the movement of the latching member 42 from the position illustrated in FIG. 5 to the position illustrated in FIG. 4, the vent opening 33 (FIG. 10) is closed at the same time that the jalousie disposed between the windows of the door 2 (FIG. 11) is closed.

In the closed position illustrated in FIG. 4, the lever member 41 actuates a switch 94 (FIG. 3) by means of which, for example, the electrical connection to the heating body for the intense under-heat of the muffle is closed as well as by means of which the blower and the after-burner are connected. The temperature in the muffle thereupon climbs to a value specified by the baking oven of approximately 500C and is held at this value to the end of the cleaning operation by the turning on and off of the heating elements of the upper and /or lower heater. The length of time for the clean-ing operation is determined by the time switching clock.

For heating the oven, it is a necessary condition that the locking mechanism be in the closed position because only then can switch 94 be actuated by means of lever member 41 to heat the oven.

By means of the switching clock, at the end of the cleaning process, only the heating bodies for the upper and lower heaters and the after-burner are disconnected. The blower for circulating the hot air is coupled outside to an impeller fan for cooling the switching members arranged outside the muffle and for cooling the bearing of the blower. The blower remains connected via contacts of the contactor 92 which are not illustrated until the temperature of the muffle drops below a lower reference value, for example 300C. Then the temperature dependent responsive switch 93 (FIG. 8) interrupts the current circuit of the excitation winding 920 of the contactor 92 whereby the abovementioned blower is disconnected and a voltage is again applied to the motor 5. The motor continues to run in the counterclockwise direction until the locking lever member 41 is free and is pulled into the position illustrated in FIG. 5 by the action of spring 6. The door of the oven can then be opened. In this position, the switch 91 is returned to the position illustrated by the dashed lines in FIG. 8 by means of a cam disc 8. The motor then remains stationary because the contactor 92 has opened.

Independent from the switching functions described above, a second cooling blower arranged between the muffle and the outer housing wall remains connected via a thermostat as long as the temperature at an especially critical position outside the muffle does not drop below a definite temperature of approximately C. This position be selected as desired.

In view of the foregoing it is evident that the control of the motor 5 described with reference to FIGS. 3,4,5 and 8 can also be used to the same advantage in connection with an oven equipped with a hinged door.

It is preferable to indicate the self-cleaning mode of operation by means of light signal, preferably a colored signal. With a baking and roasting oven having an illuminated switching cluster, it is especially simple and practical to switch from a light source emitting white light indicating normal operation to a light source emitting red light when the after-burner is energized, that is when the door is locked and/or the lower heater is energized as is the case in the self-cleaning mode of operation.

While the invention has been described by means of specific examples and in a specific embodiment, we do not wish to be limited thereto for obvious modifications will occur to those skilled in the art without departing from the spirit and scope of the invention.

We claim:

1. Baking and roasting oven for cooking food comprising a muffle structure having a front face defining a charging opening for receiving the food to be cooked; guide means fixedly mounted with respect to said muffle structure; a door assembly comprising a door extending substantially parallel to said front face, carriage means connected to said door and arranged beneath said muffle structure, said carriage means movably engaging said guide means for moving said door between open and closed positions, a pair of members of which one'is mounted on said door assembly and the other is mounted on said muffle structure, a motor means, and a motor drive means between said motor means and said other member for moving the latter relative to said one member for engaging said members such that the latter tightly close and maintain said door in a closed position.

2. An oven according to claim 1, comprising a frame, said muffle structure being secured to said frame.

3. An oven according to claim 1 wherein said door has a surface facing said opening, said oven comprising a carrier adjustably mounted to said surface for carrying the food to be cooked.

4. An oven according to claim 1, comprising a frame, said muffle structure being secured to said frame, said frame having a structural part disposed transverse of said guide means, said carriage means comprising two carriage parts engaging said guide means, and a cross rail mutually connecting the end regions of said carriage parts, said one member being mounted on said cross rail and said other member being mounted on said structural part.

5. An oven according to claim 1, wherein said carriage means comprises two carriage parts engaging said guide means, said front face of said muffle structure being an annular edge surface surrounding said charging opening, said door having a surface region lying adjacent of said carriage parts and being moveable with respect to said muffle structure so as to lie against said edge surface, said door being resiliently liased toward said annular edge surface whereby said surface region abuts said edge surface, and said motor means applying a force to said members to press said door against said edge surface, said force being directed along a line of action lying between said carriage parts.

9 6. An oven according to claim 5, said door assembly comprising angle portions projecting from said carriage parts respectively, said angle portions extending into said door so as to permit adjustment of the position of the latter with respect to said annular edge surface. 2 7. An oven according to claim 6, said door being joined to said angle portions so that the plane of said door and the plane of said annular edge surface conjointly define an acute angle when said door is open, said acute angle opening toward said carriage portions. 8. An oven according to claim 1 comprising positioning means for permitting the other of said members to move in a path having a travel component parallel to said guide means when engaged by said one member. 9. An oven according to claim 1, wherein said one member is a locking member and said other member is a latching member, said latching member comprising a wedge-shaped means, said drive means moving said wedge-shaped means relative to said locking member. 10. An oven according to claim 9, said wedge-shaped means comprising a rotatable drive shaft connected to said drive means, a sector-shaped member secured to said shaft, and said sector-shaped member having a wedge-shaped flange attached to its curved edge so as to extend in the turning direction of said shaft, said latching member comprising receiving means for receiving said sector-shaped member when the latter is rotated by said drive means, via' said shaft, and spring means mounted with respect to said receiving means for developing a force between said spring means and said wedgeshaped flange when the latter enters said receiving means.

11. An oven according to claim 10, said drive means being a motor connected to said shaft for rotating the latter about its longitudinal axis. 12. An oven according to claim 8 wherein said one member is a locking member and said other member is a latching member, and including coupling means connecting said motor to said latching member for moving the latter in a circular path when said motor is running, said locking member being an elongated member having a hook-like extension at one of its ends, and said positioning means comprising a slot at the other end of said locking member for slidably journalling the latter, a stop disposed with respect to said locking member, and a spring attached to said locking member, said slot being dimensioned to permit said spring to hold said locking member in a rest position against said stop so that said hook-like extension projects into said path whereat said latching member can engage said locking member at said rest position for pulling said locking member to a next position along said path to tightly close said door.

13. An oven according to claim 12 wherein the location at which said locking member is journalled and the axis of rotation of said coupling means lie on a line extending parallel to said carriage means.

14. An oven according to claim 13 wherein said path of travel of said latching member between said rest position and said next position comprises a travel vector extending in a direction parallel to said carriage means, said coupling means being dimensioned so that the length of said travel vector is less than the length of said slot, said spring being selected to exert sufficient force between said door assembly and said frame when said locking member is at said next position so that said door presses against said front face of said muffle structure.

15. An oven according to claim 14, comprising motor control means for controlling the operation of said motor, said control means comprising a cam disc coupled to said motor via said coupling means, switch means mounted with respect to said cam disc for disconnecting said motor in response to the actuation of said switch means by said cam when said latching member arrives at said next position, said cam disc having a contour which ensures that said switch will nOt be operated again until said latching lever has rotated to release said locking member.

16. An oven according to claim 15, said control means comprising supply means connectable to said motor, said switching means including contacts, and a change-over control contactor serially connected with said contacts and said motor to said supply means.

17. An oven according to claim 16 wherein said control contactor includes excitation means for opening and closing the contacts thereof, said control means comprising a temperature sensitive switch disposed in heat contact with said muffle structure, said temperature sensitive switch being connected to said excitation means for controlling the excitation in response to a change of temperature in said muffle structure.

18. An oven according to claim 17, comprising ancillary heater elements disposed in said muffle structure, a switching device connected with respect to said heater elements, said switching device being mounted with respect to said locking member to permit the latter to mechanically actuate said switching device when said locking member is carried into said next position by said latching member.

19. An oven according to claim 12 comprising a vent housing having a vent opening through which said housing communicates with the interior of the muffle of said muffle structure, a flap arranged in said housing for closing off said opening, a spring connected to said flap, connection means for mechanically, coupling said flap with said motor to permit said spring to hold said flap so that the latter closes said opening when said latching member is at said next position.

20. An oven according to claim 19, said housing having a second opening of substantially circular shape through which said housing communicates with the ambient, channel means of substantially circular cross section disposed with respect to said housing at said second opening for directing away vapor from the muffle interior, said channel means having a ridge projecting outwardly from its exterior surface, and an elastic seal of substantially circular shape being disposed in said second opening so as to lie opposite said ridge, said ridge having an outer diameter greater than the diameter of said channel means as well as greater than the inner diameter of said seal, whereby the latter elastically holds said ridge.

21. An oven according to claim 20, said door having inner and outer windows, jalousie slats disposed between said windows, pivot means for journalling said jalousie slats, and actuation means coupling said pivot means with said motor for closing said slats when said latching member is at said next position.

22. An oven according to claim 21 wherein said door comprises two mutually parallel walls, one of said walls being adjacent the muffle of said muffle structure, said actuation means comprising a bell crank member connected to said pivot means, a push rod moveable between first and second positions, said rod extending through said one wall for connection to said pivot means via said bell crank member, and a spring conbeing coupled to said rod to move said rod to said second position when said latching member 'goes to said next position whereby said pivot means is actuated to nected with said rod for holding the latter in said first Close Said slatsposition so that said slats are held open, said motor 

1. Baking and roasting oven for cooking food comprising a muffle structure having a front face defining a charging opening for receiving the food to be cooked; guide means fixedly mounted with respect to said muffle structure; a door assembly comprising a door extending substantially parallel to said front face, carriage means connected to said door and arranged beneath said muffle structure, said carriage means movably engaging said guide means for moving said door between open and closed positions, a pair of members of which one is mounted on said door assembly and the other is mounted on said muffle structure, a motor means, and a motor drive means between said motor means and said other member for moving the latter relative to said one member for engaging said members such that the latter tightly close and maintain said door in a closed position with respect to said guide means and said carriage means for locking said door when said door is in said closed position.
 2. An oven according to claim 1, comprising a frame, said muffle structure Being secured to said frame.
 3. An oven according to claim 1 wherein said door has a surface facing said opening, said oven comprising a carrier adjustably mounted to said surface for carrying the food to be cooked.
 4. An oven according to claim 1, comprising a frame, said muffle structure being secured to said frame, said frame having a structural part disposed transverse of said guide means, said carriage means comprising two carriage parts engaging said guide means, and a cross rail mutually connecting the end regions of said carriage parts, said one member being mounted on said cross rail and said other member being mounted on said structural part.
 5. An oven according to claim 1, wherein said carriage means comprises two carriage parts engaging said guide means, said front face of said muffle structure being an annular edge surface surrounding said charging opening, said door having a surface region lying adjacent of said carriage parts and being moveable with respect to said muffle structure so as to lie against said edge surface, said door being resiliently liased toward said annular edge surface whereby said surface region abuts said edge surface, and said motor means applying a force to said members to press said door against said edge surface, said force being directed along a line of action lying between said carriage parts.
 6. An oven according to claim 5, said door assembly comprising angle portions projecting from said carriage parts respectively, said angle portions extending into said door so as to permit adjustment of the position of the latter with respect to said annular edge surface.
 7. An oven according to claim 6, said door being joined to said angle portions so that the plane of said door and the plane of said annular edge surface conjointly define an acute angle when said door is open, said acute angle opening toward said carriage portions.
 8. An oven according to claim 1 comprising positioning means for permitting the other of said members to move in a path having a travel component parallel to said guide means when engaged by said one member.
 9. An oven according to claim 1, wherein said one member is a locking member and said other member is a latching member, said latching member comprising a wedge-shaped means, said drive means moving said wedge-shaped means relative to said locking member.
 10. An oven according to claim 9, said wedge-shaped means comprising a rotatable drive shaft connected to said drive means, a sector-shaped member secured to said shaft, and said sector-shaped member having a wedge-shaped flange attached to its curved edge so as to extend in the turning direction of said shaft, said latching member comprising receiving means for receiving said sector-shaped member when the latter is rotated by said drive means, via said shaft, and spring means mounted with respect to said receiving means for developing a force between said spring means and said wedge-shaped flange when the latter enters said receiving means.
 11. An oven according to claim 10, said drive means being a motor connected to said shaft for rotating the latter about its longitudinal axis.
 12. An oven according to claim 8 wherein said one member is a locking member and said other member is a latching member, and including coupling means connecting said motor to said latching member for moving the latter in a circular path when said motor is running, said locking member being an elongated member having a hook-like extension at one of its ends, and said positioning means comprising a slot at the other end of said locking member for slidably journalling the latter, a stop disposed with respect to said locking member, and a spring attached to said locking member, said slot being dimensioned to permit said spring to hold said locking member in a rest position against said stop so that said hook-like extension projects into said path whereat said latching member can engage said locking member at said rest position for pulling said locking membeR to a next position along said path to tightly close said door.
 13. An oven according to claim 12 wherein the location at which said locking member is journalled and the axis of rotation of said coupling means lie on a line extending parallel to said carriage means.
 14. An oven according to claim 13 wherein said path of travel of said latching member between said rest position and said next position comprises a travel vector extending in a direction parallel to said carriage means, said coupling means being dimensioned so that the length of said travel vector is less than the length of said slot, said spring being selected to exert sufficient force between said door assembly and said frame when said locking member is at said next position so that said door presses against said front face of said muffle structure.
 15. An oven according to claim 14, comprising motor control means for controlling the operation of said motor, said control means comprising a cam disc coupled to said motor via said coupling means, switch means mounted with respect to said cam disc for disconnecting said motor in response to the actuation of said switch means by said cam when said latching member arrives at said next position, said cam disc having a contour which ensures that said switch will nOt be operated again until said latching lever has rotated to release said locking member.
 16. An oven according to claim 15, said control means comprising supply means connectable to said motor, said switching means including contacts, and a change-over control contactor serially connected with said contacts and said motor to said supply means.
 17. An oven according to claim 16 wherein said control contactor includes excitation means for opening and closing the contacts thereof, said control means comprising a temperature sensitive switch disposed in heat contact with said muffle structure, said temperature sensitive switch being connected to said excitation means for controlling the excitation in response to a change of temperature in said muffle structure.
 18. An oven according to claim 17, comprising ancillary heater elements disposed in said muffle structure, a switching device connected with respect to said heater elements, said switching device being mounted with respect to said locking member to permit the latter to mechanically actuate said switching device when said locking member is carried into said next position by said latching member.
 19. An oven according to claim 12 comprising a vent housing having a vent opening through which said housing communicates with the interior of the muffle of said muffle structure, a flap arranged in said housing for closing off said opening, a spring connected to said flap, connection means for mechanically coupling said flap with said motor to permit said spring to hold said flap so that the latter closes said opening when said latching member is at said next position.
 20. An oven according to claim 19, said housing having a second opening of substantially circular shape through which said housing communicates with the ambient, channel means of substantially circular cross section disposed with respect to said housing at said second opening for directing away vapor from the muffle interior, said channel means having a ridge projecting outwardly from its exterior surface, and an elastic seal of substantially circular shape being disposed in said second opening so as to lie opposite said ridge, said ridge having an outer diameter greater than the diameter of said channel means as well as greater than the inner diameter of said seal, whereby the latter elastically holds said ridge.
 21. An oven according to claim 20, said door having inner and outer windows, jalousie slats disposed between said windows, pivot means for journalling said jalousie slats, and actuation means coupling said pivot means with said motor for closing said slats when said latching member is at said next position.
 22. An oven according to claim 21 wherein said door compRises two mutually parallel walls, one of said walls being adjacent the muffle of said muffle structure, said actuation means comprising a bell crank member connected to said pivot means, a push rod moveable between first and second positions, said rod extending through said one wall for connection to said pivot means via said bell crank member, and a spring connected with said rod for holding the latter in said first position so that said slats are held open, said motor being coupled to said rod to move said rod to said second position when said latching member goes to said next position whereby said pivot means is actuated to close said slats. 